This invention relates in general to the construction of chucks and in particular to a new and useful arrangement for coupling a false jaw to a master jaw of a chuck.
German Pat. No. 21 04 904 discloses a chucking device for turning machines with a quick change of false jaws which can be coupled to the chuck by a radial displacement of the master jaws. In that design, each master jaw is designed with a longitudinal groove in its face turned to the false jaw, with the side walls of the groove being provided with interrupted lengthwise ribs, and array of pointed teeth or similar parts. The false jaws have a fitting feather provided with interrupted lengthwise ribs, a dentation or similar part. The spaces between the teeth, or ribs, are so dimensioned that the feather can be engaged into a groove of the master jaw by an axial motion, and then positively locked by a radial motion.
To provide the master jaw grooves with teeth, separate strips must be manufactured and screwed thereto. And since the feathers of the false jaws must also be secured by screws, a high instability cannot be avoided. Further, the manufacturing costs of mating dentations are considerable since a high accuracy is required for the fitting interengagement. The primary drawback, however, is that the false jaw applies to the master jaw in the direction of rotation almost exclusively through the lateral dentation. The clamping forces thus can be transmitted only through the flanks of the teeth which are small. The high overturning torques may damage the teeth. Also, a relatively large displacement is needed for engaging and disengaging the false jaws, the overall dimensions are too large due to the screwed strips, and dirt readily deposits between the teeth.